Hey guys. I just filled up my tank after 99% of it being highway from going hunting as it is Muzzleloading season here. Averaged out my last tank was only 14.7 MPG. This again is HIGHWAY mileage. I40 @ 70mph cruise!!! I'm at a loss for what else to do. I don't want to spend a lot of $$$ to gain just a few tenths on my mileage. But with everything I've done..it just seems like I'd get better; especially on the highway.
A few months ago, you'll remember I replaced my wheel bearings and seals..and that DID give me about 4 or 5 tenths better mileage as i didn't have the parasitic drag from the bad bearing anymore and I have Royal Purple gear oil in the diffs (front and rear). I've replaced plugs last year with MC's. Run MC semi-synthetic oil and change at 5K intervals. Have a K&N cone on an Airforce one intake & Magnaflow exhaust SIDO.

About the ONLY thing left is getting electric fans and maybe trying some E-3 spark plugs. I read quite a few people get good gains (1-2 mpgs) with e fans.

I know my tires "may" be hurting me due to their semi-agressive tread (265/70R17 BFG All Terrain's kept at 50 PSI).

I was looking back on fuelly and my BEST mileage EVER was 14.9 MPGs highway and that was like almost a year ago. It was right after I cleaned the MAF and Throttle body. I know I probably need to do that again.

I KNOW I HAVE A TRUCK. I KNOW A TRUCK DOESN'T GET CAR MILEAGE.

...but I can't even get 15 mpgs on the highway...

(in my espn voice)...Come On MAN!!!!!!

Any help appreciated-----DirtySCREW

 

your enemy. Cruise control, and hills.

50psi? I only run 35.

 

Dude I've only seen that low a few times. Beats me. I don't know what would cause that. It might just be your truck's normal mpgs. Some vehicles are like that

 

Perhaps an odd question but do you take into account that the larger tires would be throwing your odometer off and making it seem like you are getting worse mileage than you really are? Unless you have a guage already calculating it

 

I agree. 5.4?? I got back from a road trip this weekend, almost completely unloaded, and got a record breaking 16.5 with my 4.6, and that included some city driving. NO engine mods at all.

We'll see how I do this next weekend when I'll be on the road with a 17' travel trailer and loaded up for hunting. I'm guessing around 11.

Just the way it goes sometimes. Depends on wind and hills too, I remember driving my stepdads Suburban 1500 up north once, mostly flat drive, mostly unloaded, but windy as all hell and I got just over 10 mpg.

 

i get about 12 - 12.5, and I dont exactly drive like an old lady...

 

I don't think so....I'm in Eastern NC...so no hills....and Cruise has ALWAYS helped me get better mileage with EVERY other vehicle I've owned....unto you get into hills or mountains of course. 50PSI is the tires MAX pressure and I'm trying to have the LEAST amount of rolling resistance possible.

Tires are STOCK size guys....so I don't know about the "larger tires" ya'll speak of. Granted they are BFG AT's ...but are stock size on stock FX4 wheels.

And yes, I have the 5.4L, 3.73 LS gears.

I'm taking the non-15 MPGs kinda personal and almost like a mission to get it there and over. It's like a project of mine if you will.--mainly because I've had an 05 Yukon 2wd that got 15-16 city and over 20-21 on the highway with the 5.3L, 3.71 gears!!!! Yea the Yukon was 2wd but it was a tad heavier than my SCREW and the gears are about the same. The only mods it had was a K&N drop in and a Flowmaster delta 50 SIDO. Granted it DID have iridium plugs and e-fans from factory.

Keep the ideas coming guys, I appreciate the help---DirtySCREW

 

i get lucky to see 12-12.5..... and im not a hard *** i drive casual.

 

lets put it this way, blown and of course I dont baby it, 14mpg best. 12-13 avg.

10 - I been playin!

 

I have a 00 Scab with a 5.4 and I average around 16 mpg. The only mod is th Gott's, so far.

 

I drive a lot of highway with my truck, with the cruse on, and milage really depends on speed. When I drive to school in MO where it is hilly and I run 75 I only get 14.5-15 mpg. But on flat ground with a speed limit of 55 so running about 62/63 I get 18-19mpg. Even if I drive slower in MO with the hills i still get better Milage. I use my gryphon to keep track of it while driving down the rd. Next time you take a trip put the cruse on 65 and I bet you see an increase in milage

 

thread like these make me appreciate my superchargers that much more...




you guys load your trucks up, install larger tires, on top of crappy 3.55 or worse gears and then complain about poor mileage

then you add worthelss throttle body spacers which restrict air flow into your engine making your mileage that much worse...


you need to remove that TB spacer, throw it as far as you can before you purchase the E-3 plugs since they are garbage and might take out your motor (if they carbon up they will burn a hole in your pistons)


e-fans, gears, and a custom tune for 91-93 octane are going to be your best bang for the buck mods that you can do

 

tarajerame-----the throttle bodyspacer was on the truck from previous owner when i bought it. I WANT to get rid of it but I don't have any standard throttle body bolts. If you know the part number of them so I CAN get standard bolts, that TB spacer is as good as gone! I know its a piece of crap!
I don't have larger tires, and I have 3.73 LS Gears.
Efans are about my only option that I can see that would realisticly provide better mileage-----DirtySCREW

 

i am all stock5.4 4x4 screw with 3.55 LS gears. Is this why im not getting more than 12?

 

Being 4x4 isnt helping you either. If your truck was 2 wheel drive i bet you would be getting around 17 on Avg. I know alot of people with 4x4 f150's and 15 mpg is all they get. Get rid of that TB Spacer and goodluck